Popen native or C import

[john9631]

I checked the codebase and there is no native subprocess module. Os defines def system(cmd: str) -> int but not popen.

I don't want to add the weight of importing pOpen from python's subprocess so decided to try using the C popen. A simplified version of my code looks like:

from C import popen(str, str) -> cobj
from C import fgets(cobj, int, cobj)

pp = popen("ls -l", "r")
print(f"pp is: {pp}, with type: {type(pp)}")

which returns

pp is: 0x0, with type: partial(__new__[...,...])

where this seems to be a pointer to type byte ( expected type 'Ptr[byte]' ). Does anyone know how I should be handling popen's return object in codon? My goal is to be able to manipulate the resulting string or array of strings.

[arshajii]

Hi @john9631 -- popen should actually take two cobjs (which correspond to the char * arguments in C). Here is the modified code which also calls fgets:

from C import popen(cobj, cobj) -> cobj
from C import fgets(cobj, i32, cobj) -> cobj

pp = popen("ls -l".c_str(), "r".c_str())

n = 1000
p = cobj(n)
fgets(p, i32(n), pp)
print('read:', str.from_ptr(p))

[john9631]

Thanks.

I extended it to my real problem and it worked perfectly. You've done a lovely job of keeping this as simple as possible.